PT96783A - PROCESS FOR THE PREPARATION OF THERAPEUTIC NUCLEOSIDES AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM - Google Patents

Description

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Description of the invention patent of THE WELCOME EOUNBATIGN LIMITED, British, industrial and commercial, headquartered at Unicom House, 160 Euston Road, London NW1 2 EP, England (inventors: Saad George Ra him, Mirjana Yladimira Boguno-vic- Batchelor and George Edward Tranter, residing in England) for " PROCESS FOR THE PREPARATION OF THERAPEUTIC NUCLBOSIDES AND THE PHARMACEUTICAL COMPOSITIONS CONTAINING THEM. The present invention relates to certain 3'-fluoro-oleoside analogs, to their pharmaceutically acceptable derivatives, further referring to the use of such analogues and to derivatives thereof in therapy, particularly for the treatment or prophylaxis of certain viral infections. BAD.

One group of viruses that has recently taken on particular importance is that of retroviruses. Retroviruses are a sub-group of RNA viruses, which, in order to replicate, must first " reverse transverse " the RNA from its genome to the DNA (" transcription " describes conventionally the synthesis of RNA from DNA). When in the form of DNA, the viral genome may be incorporated into genome 1

of the host cell, allowing it to take advantage of the host cell transertion / translation mechanism for replication targets. as soon as incorporated, the viral AM is virtually indistinguishable from the AM of the host and, at this stage, the virus may persist for the life of the cell.

One of the retrovirus species, the Human Immunodeficiency Virus (HIV), has been reproducibly isolated from humans with Acquired Human Immunodeficiency Syndrome (AIDS) or with the symptoms that often precede AIDS. AIDS is an immunosuppressive or immuno-destructive disease and predisposes patients to fatal opportunistic infections. AIDS is characteristically associated with a progressive lack of T cells, especially its helper-subunit containing the OIT2 surface marker. HIY is cytopathic and appears to preferentially infect and destroy the T cells containing the label and it is generally considered that HIV is the etiologic agent of SIM.

Since the discovery that HIY is the etiologic agent of AIDS, several proposals have been made for the preparation of anti-HIV chemotherapeutic agents that may be effective in the treatment of AIDS. Thus, for example, the disclosure of European Patent 3P 196185 mentions 3Î ±, 2Î ± -oxido-3Î ± -deoxythymidine (which has the accepted name zidovudine), and pharmaceutically acceptable derivatives thereof and relates to their use in the treatment of infections human immunodeficiency virus (AIDS) retroviruses and associated clinical conditions. Other nucleoside derivatives which have been suggested for HIV infections include the 3'-fluoronueleosides described for example in European Patent No. 0254 268 and in International Patent Specification 88/0050.

Another group of viral pathogens of major worldwide consequence are hepatitis viruses,

the hepatitis B virus (HBV). HBV is more frequent in Asian countries, and is prevalent in the southern Sahara. The virus is etiologically associated with primary hepatocellular carcinoma and is thought to be the cause of 80% of the global liver cancers. In the United States more than ten thousand people are hospitalized for diseases caused by HIY in each year, and 250 people die on average with the disease fulminante. The United States currently contains an estimated 500,000 to 1 million infected carriers. Chronic active hepatitis will develop in more than 25% of the carriers and often progresses to cirrhosis. It is estimated that five thousand people die of HBY related cirrhosis each year in the United States of America, and that perhaps a thousand die of HBY related liver cancer. Thus, there is a great need for effective antiviral agents, both to control chronic infection and to reduce progression to hepatocellular carcinoma.

The clinical effects of HBY infection range from headache, fever, malaise, nausea, vomiting, anorexia and abdominal pain. Virus replication is usually controlled by the immune response, with a course of recovery lasting for weeks or months in humans, but the infection may be more severe leading to a persistent chronic liver disease as described in " Viral Infections of Hu mans " (second edition, Ed., Evans, A.S. (1982) Plenum Publis-hing Corporation, New York), and Chapter 12 describing the etiology of viral hepatitis infections.

It is now surprisingly found that the 3'-fluoro-2 ', 3'-dideoxynucleosides referred to below have a potent activity against retroviruses such as HIV, as well as HBY.

According to the present invention there is provided the use of 3, 4-fluoro-2 ', 3'-dideoxynucleosides of the formula (I):

(D

I

(for example methoxymethyl, ethoxymethyl), cyanomethyl, azidomethyl, mono-, di- or trihalomethyl (e.g. trifluoromethyl), nitro, 2-haloalkynyl (for example methylthiomethyl, or ethylthiomethyl), (for example methoxy) or alkyl (1-4C) thio (for example methylthio); or a pharmaceutically acceptable derivative thereof for the preparation of a medicament for the treatment or prophylaxis of a retroviral infection, particularly an infection caused by the human immunodeficiency virus; or viral infection of hepatitis B.

The compounds of formula (I) and their pharmaceutically acceptable derivatives are hereinafter referred to as compounds according to the invention. The term " alkyl " is used herein to describe Î ±, β

straight or branched chain alkyl groups.

A further aspect of the invention is included a method for the treatment of a viral infection, particularly retroviral or hepatitis B virus infections of a mammal including man comprising treating the mammal with an effective antiviral amount of a compound of according to the invention. *1

Compounds of formula (I) wherein R1 is azidomethyl or aminomethyl are defined in German patent application DD268475 which refers to these compounds as tactical virus agents. r 1

Compounds of formula (I) wherein R is methyl thiorecyl, methoxymethyl or trifluoromethyl are generally encompassed by reference in European Patent Application No. 0322384, but are not specifically referred to therein. It has now been discovered that such compounds have advantageous properties, including a particularly potent anti-HIV activity. Accordingly, the use of the compounds in the treatment of HIV-related conditions constitutes a further aspect of the present invention. European Patent 1 0254 268 discloses a compound of formula (I) wherein R 2 represents bromomethyl as an intermediate for the preparation of 3'-fluoronucleosides, but without any reference to the medical use of this compound.

Compounds of formula (I) wherein R4 is alkyl (2-40) thiomethyl or (2-40) methyl alkoxy are also included in the present invention. The present invention further includes 3'-fluoro-2 ', 3'-dideoxynucleosides of formula (IA). - 5 - I t

(for example methylthiomethyl, or ethylthiomethyl), (1-4C) alkoxy methyl (for example methoxymethyl, ethoxymethyl), cyanomethyl, mono-, di- or trihalomethyl (for example trifluoromethyl), nitro, 2-haloalkynyl (e.g. 2-chloroethinyl), (1-4C) alkoxy (eg methoxy) or (1-4C) alkylthio (for example methyltol); or a pharmaceutically acceptable derivative thereof for use in medical therapy in the treatment or prophylaxis of viral infections, especially retroviral infections and viral hepatitis B infection.

Examples of retroviral infections that may be treated according to the invention include human retroviral infections such as HY-I, HY-2 and human T-cell photropic virus (HLTY), for example HTLV-1 infections or HTIiV-2.

The compounds according to the invention are also useful for the treatment of associated clinical conditions. with retroviral infections, for example, SIM,

Kaposi, thrombocytopenic purpura, AIDS-related complex (ARC), generalized progressive lymphadenopathy (PCI), and HIV-bearing or HIV-seropositive patients as well as chronic neurological conditions such as multiple sclerosis or spastic paraparesis tro piicai.

The compounds according to the invention may also be used for the treatment or prophylaxis of infections caused by AM viruses which, like retroviruses, are incorporated into the host genome during its life cycle, i.e., viruses such as for example the hepatitis B virus. Thus, the compounds of the invention are also provided for the use in the treatment or prophylaxis of infections caused by such retrovirus-like viruses. The present invention further provides novel compounds of formula (IB) s

- - - - - - - - - - - - - - - - - - - - - - - -

(for example methylthiomethyl, or ethylthiomethyl), (1-4C) alkoxy (for example methoxymethyl, ethoxymethyl), cyanomethyl, mono-, di- or tri- halogenoethyl (e.g. trifluoromethyl), nitro, 2-haloalkynyl (e.g. 2-chloroethynyl), (1-4C) alkoxy (eg methoxy) or alkyl (1-4C) thio (for example methylthio); or a pharmaceutically acceptable derivative thereof.

Examples of the compound of formula (ΓΒ) above include the following compound of formula (IC):

(For example 2-chloroethylamino), (1-4C) alkoxy (for example methoxy), and (1-4C) alkylthio group, (for example methylthio); or a pharmaceutically acceptable derivative thereof.

Further examples of compounds of formula (IB) above include the compounds of formula (IB)

in which R 1 represents a cyanomethyl, nitro, 2-haloalkyl (e.g. 2-chloroethynyl), alkoxy (1-4C) group (for example methoxy) and the (1-4C) alkylthio group (for example methylthio); or a pharmaceutically acceptable derivative thereof.

The above formulas (1), (IA), (IB), (IO) and (IB) represent the compound in the form of otho. It should be noted that the compound may also exist in the corresponding Î ± -enol token form.

Preferred compounds of formula (IB) include those in which R represents (1-4C) alkylthiomethyl or (1-4C) alkoxy; or a pharmaceutically acceptable derivative thereof.

Particularly preferred compounds of formula (IB) include: 9-1,2 ', 3'-dideoxy-3'-fluoro-5-methoxymethyluridine

(2) 2 ', 3'-dideoxy-3'-fluoro-5-ethoxymethyluridine (3) 2', 3'-dideoxy-3'-fluoro-5-methylthiomethyluridine

By " pharmaceutically acceptable derivative " is meant any salt, ester, or salt of such a pharmaceutically acceptable ester of a compound of formula (I) or any other compound which, upon administration to the patient, is capable of providing or in-directly) that compound or its methanolite or antiviral active residue.

Preferred esters of the compounds of formula (I) include esters of carboxylic acids wherein the non-carbonyl radical of the ester moiety is selected from straight or branched chain alkyl groups (for example methyl, n-propyl, n- (for example benzyl), aryloxyalkyl (e.g. phenoxymethyl), aryl (for example optionally substituted phenyl and halogen, (1-4C) alkyl or (1-4C) alkoxy) ) or amino); sulfonate esters such as alkyl or alkylarylsulfonyl (e.g. methanesulfonyl); amino acid esters (for example L-valyl or ε-isoleucyl); and esters of mono, di or triphosphate. In such esters unless otherwise stated, any alkyl radical present advantageously contains 1 to 18 carbon atoms, particularly 1 to 4 carbon atoms. Any aryl radical present in such esters advantageously comprises a phenyl group. Any reference to any of the above-mentioned compounds also includes a reference to a pharmaceutically acceptable salt thereof.

Examples of pharmaceutically acceptable salts of the compound of formula (I) and pharmaceutically acceptable derivatives thereof include base salts, for example those derived from a suitable base, such as the 10-

alkali metal (for example sodium), alkaline earth metal (for example magnesium), ammonium and NX + (wherein X1 is (1-4C) alkyl). The physiologically acceptable salts of the hydrogen atom or the amino group include salts of organic carboxylic acids such as acetic, lactic, tartaric, malic, isethionic, lactobionic and succinic acids; organic sulfonic acids such as methanesulfonic, ethanesulfonic, benzenesulfonic and p-toluenesulfonic acids and inorganic acids such as The physiologically acceptable salts of a compound of a hydroxy group include the anion of said compound as for example Na +, HH +, and X + (wherein X is an alkyl- (1-hydroxymethyl) -40).

The compounds according to the invention may be used in combination with other therapeutic agents for the treatment of the conditions or infusions referred to above. Examples of such other therapeutic agents include agents which are effective for treating infections or conditions associated with ΗΠΓ such as 3β-azido-3, -deoxythymidine (zidovudine), other 2 ', 3'-dideoxynucleosides such as 2β, , 3'-dideoxycytidine, 2,3'-dideoxyadenosine and 2 ', 3'-dideoxyinosine, earbovir, acyclic nucleosides (for example acyclovir), 21? -Demetintimidine, interferons such as Q -in- such as pro-benocid, nucleoside transport inhibitors such as pyrimidole, as well as immunomodulators such as interleukin II and granulocyte colony stimulating factors granulocytes, erythropoietin, phosphonoformic and soluble acid, and the like. their genetically derived derivatives. The component compounds of such combination therapy may be administered simultaneously, in separate or combined formulations, or at different heights, for example sequentially, so as to obtain a combined effect.

The compounds according to the invention, also a -

(including " buccal and sub-lingual), vaginal, parenteral (including subcutaneous, intramuscular, intravenous) and intravenous (intramuscular) and intradermal) and pulmonary. It should also be noted that the preferred route will vary with the condition and age of the patient, nature of the infection and the active ingredient chosen.

In general, a suitable dose for each of the above antiviral injections designated, for example, HIY, HBV is in the range of 0.5 to 120 mg per kilogram of body weight per day, preferably in the range of 1 to 90 mg per kilogram of body weight per day and more preferably in the range of 2 to 60 mg per kilogram of body weight per day. The desired dose is preferably presented in the form of two, three, four, five, six or more sub-doses administered at appropriate intervals throughout the day. These sub-doses may be administered in the form of dosage units, for example, containing 1 to 1500 mg, preferably 5 to 1000 mg, and more preferably 10 to 700 mg of active ingredient per dosage unit form. The active ingredient should ideally be administered so as to achieve peak plasma concentrations of the cereal active compound from 0.25 to about 100 μM, preferably about 0.5 to 70 μ, most preferably about This may be achieved, for example, by intravenous injection of a 0.1 to 5% solution of the active ingredient, optionally in saline, or orally administered, for example, under the conditions of administration. form of a tablet, capsule or syrup containing about 0.5 to about 100 mg / kg of the active ingredient. Desirable blood levels may be maintained by continuous infusion to provide about 0.01 to about 5.0 mg / kg / hour or by [intermittent infusions containing about 0.4 to about 15 mg / kg of the active ingredient

While it is possible that the topical ingredient is administered alone, it is preferable to present it in the form of a pharmaceutical composition comprising at least one active ingredient as defined above in association with one or more pharmaceutically acceptable carriers and optionally other therapeutic agents. Each vehicle must be " acceptable " in the sense of being compatible with the other ingredients of the composition and not being detrimental to the patient.

Formulations include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal and parenteral (including subcutaneous, intramuscular, intravenous and intradermal) administration. The compositions may conveniently be presented in the form of a dosage unit and may be prepared by any process well known to those skilled in the art. Such processes include the step of ashing the active ingredient with the carrier which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately admixing the active ingredient with liquid carriers or finely divided solid carriers or both, and then conforming the product.

Compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; in the form of powders or granules; in the form of a suspension or suspension in an aqueous or non-aqueous liquid; or an oil-in-water or water-in-oil emulsion. The active ingredient may also be presented in the form of a bolus, e-lectern or paste.

A tablet may be prepared by compression or molding, optionally with one or more accessory ingredients. - 13 -

The tablets may be prepared by the use of a suitable machine in a fluid form such as powders or granules, optionally mixed with a binder (for example povidone, gelatin, hydroxypropylmethyl cellulose), a lubricant, an inert diluent, preservative, disintegrant (for example sodium starch glycolate, crosslinked povidone, reticulated sodium carboxymethyl cellulose) surfactant or dispersing agents. Molded tablets may be obtained by molding into a suitable machine from a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may be optically coated or covered and may be formulated so as to provide a lens or controlled release of the active ingredient contained therein, for example using hydroxypropylmethyl cellulose in various proportions to provide the desired release profile. The tablets may optionally be coated with an enteric coating, to provide delivery in different parts of the digestive system of the stomach.

Formulations suitable for topical administration in the mouth include lozenges comprising the active ingredient in a flavored base, generally saoose and ethanol or tragacanth; lozenges comprising the active ingredient in an inert base such as for example gelatin and glycerin, or sausage and acacia; and mouthwashes comprising the active ingredient in a suitable liquid carrier.

Pharmaceutical compositions for topical administration according to the present invention may be formulated as ointment, cream, suspension, lotion, powder, solution, paste, gel, spray, aerosol or oil. Alternatively, a formulation may comprise a dressing such as an adhesive patch or plaster impregnated with active ingredients and optionally one or more excipients or diluents. The 14-

vehicles which may be used include for example polyhydric alcohols such as polyethylene glycols, propylene glycol or glycolol. Suitable excipients are those known as suitable.

Formulations for rectal administration may be in the form of a suppository with a suitable base comprising for example cocoa butter or a salicylate.

Formulations suitable for vaginal administration may be presented in the form of pessaries, buffers, creams, gels, pastes, foams or sprays containing, in addition to the active ingredient, the carriers which are known and suitable.

Compositions suitable for parenteral administration include aqueous and non-aqueous isotonic sterile injectable solutions which may contain anti-oxidants, buffers, stereoisotopes and solutes which render the composition isoniconic with the patient's blood being treated; and sterile aqueous and non-aqueous suspensions which may include suspending agents and thickening agents and liposomes or other microparticulate systems which are designed to bring the compound to the components of the blood or one or more organs. The compositions may be presented in multi-dose or multi-dose containers, for example, ampoules and phrases, and may be stored in a freeze-dried condition requiring only the addition of a sterile liquid carrier, for example, water for injections , immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from powders, granules and sterile tablets of the type previously described.

Preferred unit dosage compositions,

are those which contain a daily dose or unit, daily sub-dose, as referred to herein, or a suitable fraction thereof, of an active ingredient.

It will be understood that in addition to the particular ingredients mentioned above the compositions of this invention may include other agents conventional to the type of composition in question, for example those suitable for oral administration may include other agents such as sweeteners, thickeners or flavoring agents.

The compounds according to the invention may also be presented for use in the form of veterinary formulations, which may be prepared, for example, by processes which are conventional.

The compounds of formula (I) and their pharmaceutically acceptable derivatives can be prepared by the method of the formula (IB) in which (A) is a compound of formula (IB) (1-4C) alkylthio, (1-4C) alkoxy, methyl, cyanomethyl, azidomethyl, mono-, di- or trihalomethyl, nitro, 2-haloalkynyl or aminomethyl groups, a protecting group of a compound having the formula (II)

- - - - - - - - - - - - - - - -

(II) in which QR is a protected hydroxy group and X is equal to R1 in the resulting compounds of formula (I); (B) for the preparation of compounds of formula (I) in which R 1 represents an alkoxy group (1-4C), reacting a compound of formula (IY)

- 17 -

in which Y is a hydroxyl group, with an agent (s) and / or in conditions which serve to alkylate the 5-hydroxy group on the uracil base. (0) for the preparation of compounds of formula (I) in which R1 represents a (1-4C) alkylthio group, reacting a compound of formula (IV) in which I represents a substitutable group with an agent (s) and / or under conditions which serve to introduce an alkyl (1-40) thio group in the 5-position (D) to react a compound of formula (V)

in which is as defined above and Z represents a precursor group for the fluorine group, with an agent (s) and / or under conditions which serve to convert said precursor group to a fluorine group; or (E) reacting a pyrimidine base of formula (VI): â € ƒâ € ƒâ € ƒâ € ƒâ € ƒâ € ƒâ € ƒâ € ƒ

in which R1 is as defined above, or a functional equivalent thereof, with a compound which serves to introduce the desired ribophoranosyl α-nel at the 1-position of the pyrimidine base of formula (VI); and then either simultaneously carrying out one or more of the following optional conversions: (i) removing any remaining protecting groups; (ii) when forming a compound of formula (I), said compound is dissolved in a pharmaceutically acceptable derivative thereof; (iii) when forming a pharmaceutically acceptable derivative of a compound of formula (I), converting said derivative into a compound of formula (I), or a different derivative thereof. The present invention includes a process for the preparation of the compound of formula (IB) and its pharmaceutically acceptable derivatives according to the above process for the preparation of the compound of formula (I) and pharmaceutically acceptable derivatives thereof. In the above-described process according to the invention it should be noted that the starting compounds of the formulas (II), (III), (IV), (V) and (VI), as well as the agents and conditions mentioned above, will be selected from those known in the chemistry of the synthesis of nueleoside. For example,

described in Nucleic Acid Chemistry, Improved New Synthetic Pro cedures, Methods and Teeniques. Ed. LB Townsend and S, S. Tipson-Wiley Interscience (1978) and Nucleoside Analogues: Che-mistry, Biology and Medical Applications, Ed. RT Walker, E. de Clercq and F. Eckstein, NATO Advanced Study Instituted, Plenum press (1979) Examples of such converting procedures are as follows for guidance and it should be appreciated that they may be modified in a conventional manner depending on the compound of formula (I) sought. In particular, when describing a conversion which would otherwise result in an undesirable reaction of labile groups then such groups may be conventionally protected, with the subsequent removal of the protecting groups upon completion of the conversion.

In the process (A) the protected hydroxy group (OR) may be for example an Ister grouping in particular (1-6C) alkanoyloxy (for example acetyloxy) or aroyloxy or alkaryloxy (for example toluoyloxy), or an alkoxycarbonyloxy for example methoxycarbonyloxy); or an ether group such as trialkylsilyloxy (e.g. t-butyldimethylsilyloxy) or an Î ± -rallyloxy group (for example triphenylmethyloxy); or a phosphate group.

Such groups may be converted, for example, by hydrolysis to the desired hydroxy compound. A particularly preferred hydroxy protecting group is an acyloxy group which may, for example, be hydrolyzed under basic conditions, for example with sodium methoxide / methanol, aqueous methylamine or ammonia. The group may alternatively be enzymatically hydrolyzed, for example, by esterase.

Another preferred hydroxy protecting group is the t-butyldimethylsilyloxy group which may be removed for example by acid hydrolysis or using tetrabutyl fluoride,

(TBAF).

In process A the starting compound of formula (II) wherein X is alkyl (1-40) thiomethyl, (1-4C) alkoxy, cyanomethyl, azidomethyl, or aminomethyl may be conveniently prepared from the compound of formula (III)

O

CH₂Cl₂

(III) wherein OR is as previously defined and 1 is a suitable substitutable group other than hydroxy, such as a halogen group for example bromo, an alkyl- or arylsulfonyl-group, such as a trifluoromethanesulfonyl, methanesulfonic nyl or p-toluenesulfonyl or a secondary amino acyclic or cyclic group, such as dimethylamino or pyrrolidinyl, typically by treatment with a suitable nucleophilic reagent for example in the case where X is azidomethyl, sodium azide in a polar solvent for example acetone at elevated temperature or when X is aminomethyl by treatment with ammonia under the same conditions.

Compounds of formula (II) wherein X is alkyl 21-1

(1-4C) alkylthiomethyl, for example methylthiomethyl, may conveniently be prepared from a corresponding compound of formula (III) wherein " is as defined above for example bromine, methanesulfonyl or pyrrolidinyl by treatment with sodium thiomethoxide. Similarly, compounds of formula (II) wherein X is (1-40) alkoxy methyl, for example methoxymethyl or ethoxymethyl may be prepared from compounds of formula (III) wherein R1 is a substitutable group e.g., bromine, methanesulfonyl or pyrrolidinyl by treatment with methanol or ethanol respectively.

Compounds of formula (II) wherein X is a methyl group substituted by one or more halogen atoms may conveniently be prepared for example by the procedures described in Matulie Adamic et al., 1988 J. Med. Chem. 31, 1642-1647.

Compounds of formula (II) in which X 1 is a halomethyl group, for example fluoromethyl may, for example, be conveniently prepared from compounds of formula (III) wherein for example bromine or hydroxy typically in which case D 1 is bromo by treatment with a fluorinating agent such as, for example, silver fluoride in a polar solvent, for example acetonitrile at room temperature. In which case L1 is hydroxy by treatment with a fluorinating agent such as dimethylaminosulfur trifluoride (MSI) in the presence of an inert solvent, for example dichloromethane (DCM) at reduced temperature.

Compounds of formula (III) wherein it is hydroxy may conveniently be prepared from compounds of formula (III) wherein L 'is Jialogeneous typically in the presence of a base such as sodium hydrogencarbonate (NaHCO 3) in the aqueous organic solvent, for example tetrahydrofuran aqueous solution (IEF) at room temperature. 22 -

Compounds of formula (II) wherein X is a dihalomethyl group, for example difluoromethyl, may be prepared by fluorination of a compound of formula (II) wherein X is a formyl group by reaction with fluorination agent such as DAST in the presence of an inert organic solvent such as BCM at reduced temperature. This compound may itself be obtained by oxidation of a compound of formula (III) wherein R1 is hydroxy, typically by reaction with an oxidizing agent for example tetrapropylammonium perruthenate (EPAP) with a co-oxidant such as 4-methylmorpholine N-oxide in an inert solvent for example BOM at room temperature. Compounds of formula (III) wherein R1 is hydroxy may be prepared as described above.

Compounds of formula (II) wherein X is a trihalomethyl group, for example a trifluoromethyl group, may conveniently be prepared by treatment of a compound of formula (II) wherein X is a substitutable group such as, for example a halogen atom, for example iodine with a suitable trihalomethyl precursor such as iodotrifluoromethane in the presence of a metal such as copper in a solvent such as hexamethylphosphoramide at elevated temperature.

Compounds of formula (II) wherein X is a halogen moiety may be prepared, for example, by the procedure described by Robins and Ool, 1982. Can. J. Ghem 60, 554, i.e. by halogenation of a compound of formula (II) wherein X is hydrogen, for example, by iodination using sodium monostearate, for example in DMF, bromination using broth, example in glacial acetic acid and chlorination using an iodobenzene chlorine complex, for example in glacial acetic acid. Compounds of formula (II) wherein X is hydrogen may be prepared by blocking the 5 'position of a compound of formula (IV) wherein Y is hydrogen in a conventional manner, for example in the case of -

acyl groups by treatment with a suitable acyl halide, for example a chloride or anhydride.

Compounds of formula (17) wherein I is hydrogen may be prepared as described, for example, by Kowollick et al. J. Prackt Chem. 1973 315 (5) 895-900.

Compounds of formula (III) wherein GR is as defined above and L 1 is a suitable substitutable group other than hydroxy may be prepared by well-known procedures, for example in the case where I is halogen by treatment of a compound (II) wherein X is methyl with a suitable halogenation system, for example in the case where it is bromine, R-bromoscincinimide in the presence of azobisisobutyrophenyl (AIBN) and irradiation with U7 light.

Compounds of formula (III) wherein it is an alkyl- or arylsulfonyloxy group may conveniently be prepared from the corresponding compound of formula (III) wherein h1 is hydroxy by treatment with a suitable sulfonyl halide, for example, in in which case it is methanesulfonyl chloride, methanesulfonyl chloride, typically under basic conditions. Compounds of formula (III) wherein R1 is hydroxy may be prepared as described above or alternatively by the hydroxymethylation of compounds of formula (II) wherein X is hydrogen according to the procedure of Kahi-lainen et al :, Acta Chemiea Scandinavian B, 1985, 39, 477.

Compounds of formula (III) wherein it is a secondary amino group may be prepared according to the procedure of Badman et al., J. Chem. Soc. Ghem. Commun. 1987, 32, from compounds of formula (II) wherein XI is hydrogen and GR is hydroxy or a protected hydroxy group by reaction with the appropriate amine, for example dimethylamine or pyrrolidine, in the presence of a formylation, for example, formaldehyde. - 24 -

The substitution capacity of the L group in the compounds of formula (III) wherein R1 is a secondary amino group may be increased by quaternization of the nitrogen atom of an amino group, for example by reaction with a alkyl halide such as methyl iodide typically in an alcoholic solvent preferably methanol to produce the corresponding methyldi of the amine.

Compounds of formula (II) wherein X is hydrogen or methyl and OR is a protected hydroxy group may be prepared from the corresponding compounds of formula (II) wherein OR is hydroxy by treatment with an acyl halide for example, the chloride, or hydroxide to provide the corresponding ester or with a suitable alkyl or silyl halide to give the corresponding ether or silyl ether.

Compounds of formula (II) wherein X is hydrogen or methyl and OR is hydroxy may be prepared in the same manner as described, for example, by Kowolliek et al., J. Prackt Chem. 1973 315 (5) 895. The compound of formula (II) wherein X is nitro, can be conveniently prepared by the process described by Huang and Torrence 1977 < J. Qrg. Chem. 42 (24) 3821, that is by treatment of a compound of formula (II) wherein X is hydrogen and R is a blocking group such as for example phosphate with a nitrating agent, for example ammonium tetrafluoroborate in inert solvent, for example sulfolane at room temperature.

Compounds of formula (II) wherein X is hydrogen may conveniently be prepared by blocking the 5 'position of the compounds of formula (17) wherein Y is hydrogen in a conventional manner, in the case of blocking groups

of phosphate by treatment, for example, with a phosphorylating agent such as phosphoryl chloride in a phosphate solvent such as triethyl phosphate at reduced temperature. The corresponding compound of formula (I) wherein Y is hydrogen may be prepared as described by Kowollick et al., (1973).

Compounds of formula (II) wherein X is 2-haloalkynyl may conveniently be prepared by dehydrohalogenation of a compound of formula (II) wherein X is the symmetrical 1,2-dihalovinyl group corresponding typically by treatment with 1,4-diazymethylcyclopent-7-ene (BBU) in the presence of an inert solvent such as dichloromethane at room temperature. The 1,2-dihalovinyl precursor may conveniently be prepared by the dihalogenation of a compound of formula (II) wherein X is the corresponding ethynyl group by reaction with a brominating agent, for example tertiary butyl bromide in the presence of a polar aprotic solvent, for example, dimethyl sulfoxide (SOM) at room temperature.

The latter compound of formula (II) may be prepared by blocking the 5'-hydroxy group of the corresponding alcohol by treatment with a suitable acyl halide, for example a chloride or anhydride in the presence of pyridine at ambient temperature. Said alcohol may be prepared, for example, in the manner described in European Patent Application No. 88850370.3 or by analogy thereto. The process B can be carried out, for example, by the process described by J. In et al. 1988 J. Med. Ohem. 31 336-340, i.e. by treatment of a compound of formula (IY) in which Y is hydroxy with an alkylating agent such as 26-

for example an alkyl halide, for example, methyl bromide in the presence of a base, such as sodium hydroxide in aqueous methanol at room temperature. The compound of formula (I) wherein Y is hydroxy may conveniently be prepared by hydroxylation of a compound of formula (IY) wherein Y is halogen, for example by treatment with triethylamine in aqueous methanol at ambient temperature. The latter compound of formula (IY) may be prepared by halogenating a compound of formula (IY) wherein Y is hydrogen, for example, using bromine in aqueous (tetrahydrofuran). Compounds of formula (IV) wherein Y is hydrogen may be prepared as described above. Process 0 may be effected by treatment of a compound of formula (IY) wherein Y is a suitable substitutable group, for example chloromereurium with a thiolation reagent capable of replacing a substitutable group with an alkyl group (1-4C) for example, in the case where Y is chloromereurium, (1-4C) alkyl disulfide in the presence of a palladium catalyst such as lithium tetrachloride and palladium (MgPdO4) in a polar solvent such as methanol . The compound of formula (IY) wherein Y is a substitutable group may be prepared from a compound of formula (IY) wherein Y is hydrogen, for example, in the case where Y is chloromereurium, by treatment with mercuric in the presence of a chloride salt such as sodium chloride in a solvent, for example water, at elevated temperature. The compound of formula (IY) wherein Y is hydrogen may be prepared as described above. - 27 -

With respect to the subject (B) this may be effected, for example, by treatment of a compound of formula (V) wherein 2 represents a substitutable group for example hydroxy or organosulfonyloxy such as methanesulfonyloxy or trifluoromethanesulfonyloxy with an agent of suitable fluorination such as dimethylaminosulfur trifluoride, potassium fluoride, potassium hydrogen fluoride, or tetra-n-butylammonium fluoride, the process (E) may be effected for example by treatment of the pyrimidine base of formula (VI) or a salt thereof or protected derivative thereof with 3Î ± -deoxy-3Î ± -fluorothymidine for example in the presence of a suitable dopant transfer enzyme or an organic catalyst such as trimethylsilyltrifluoromethane sulfonate in an aqueous solution buffered.

Alternatively, compounds of formula (VI) wherein R 2 and R 3 are as defined above, or a salt or protected derivative thereof can be chemically coupled with an α 2 -deoxy-activated derivative of 2,3-dideoxy-3-fluoro ribose by well-known methods, for example Hucleoside Analoguess Ohe-mistry, Biology, Medical Application, Ed. RT * Walker, E. de Clercq and E. Eckstein, BAIO Advanced Study Instituted, Plenum press (1979) dideoxy-3-fluoro ribose can be prepared according to the Asahi Glass process as described in Japanese Laid-Open Patent Application JP0129390. Compounds of formula (VI) wherein Rx is as defined above or a protected salt or derivative thereof may be obtained commercially or prepared by processes analogous to those described in processes (A), (B) and (O) above for the preparation of compounds of formula (I) having the substituents R " " correspondents. The compound of formula (I) may be converted 28 -

to a pharmaceutically acceptable ester thereof by reacting it with a suitable esterifying agent, for example, a halide or anhydride. The compound of formula (I) including esters thereof may be converted into its pharmaceutically acceptable salts in a conventional manner, for example by treatment with a suitable base. An ester or salt of a compound of formula (I) may be converted into the parent compound, for example by hydrolysis.

The following Examples are intended for illustrative purposes only and are not intended to limit the scope of the invention in any way. The term " active ingredient " as used in the Examples refers to a compound of formula (I) or a pharmaceutically acceptable derivative thereof.

According to a further aspect of the invention there are also provided: a) compounds of formula (IB) or pharmaceutically acceptable derivatives thereof for use in therapy; b) pharmaceutical compositions using the compound of formula (IA) or (IB); or a pharmaceutically acceptable derivative thereof, in association with a pharmaceutically acceptable diluent or carrier, c) the use of a compound of formula (IA) or (IB); or a pharmaceutically acceptable derivative thereof for the preparation of a medicament for the treatment or prophylaxis of a retroviral infection, particularly a Human Immunodeficiency Virus infection or a hepatitis B virus infection. (d) a method for the treatment or prophylaxis of a viral infection, particularly a retroviral infection or the hepatitis B virus of a mammal including humans, which comprises treating the mammal with an effective antiviral amount of a compound of formula (IA) or (IB); or -

a pharmaceutically acceptable derivative thereof.

The following Examples are provided as an i-lustration of the present invention and should not be construed as limitations thereof.

To a stirred solution of 2 ', 3'-dideoxy-3'-fluoro-5- (tert-butyldiphenylsilyl) (15 g, 0.06 mol) in tert-butylchlorodiphenylsilane (19.2 ml) in dry EM 3 (dimethylformamide) (210 ml) was added imidazole (8.4 g, 0.12 mol). After stirring at room temperature overnight, the solvent was evaporated and the residue was partitioned between ethyl acetate / water (450 ml each). The aqueous phase was further extracted with ethyl acetate ( The combined organic fractions were dried (Na2 SO4) and evaporated to dryness. Trituration of the residue with ether followed by storage at 0 ° C gave the title compound as a white solid: 200MHz HMN (10H, m, aromatic Ms), 7.45 (1H, s, H-6), 6.2 (1H, dt, 1H), 5.4 (1H, bs, 1H) (1H, dt, H-4 ', J 4, F = 27.5), 3.87 (2H, m, H-5'), 2.6-2.1 (2H, m, H-2 *), 1.5 (3H, s, -CH 3)) 1 .05 ppm (9H, s, tBu). b) 2, 5β-Bideoxy-3Î ± -fluoro-5-hydroxymethyl-5β- (tert-butyldi-phenylsilyl) uridine

A solution of 2,3-dideoxy-3-fluoro-5-methyl-5,10-tert-butyldiphenylsilyl) uri dine (8 g, 0.016 mol) in anhydrous ml) was added over a period of 20 minutes to a stirred suspension of N-bromosuccinimide (3.76 g, 0.02 mol) and ΑΙΒΪΓ (0.005 g) in dry CH2 Cl2 (50 ml) which was irradiated under an atmosphere of nitrogen with -30-vi.

a 100 W tungsten lamp. When the addition was complete, the reaction mixture was stirred for an additional 10 minutes, cooled, filtered and the filtrate evaporated to dryness. The remaining residue was dissolved in THF (tetrahydrofuran) (150 ml) and NaHCO 3 (1.7 g) in water (51 ml) was added. The mixture was stirred at room temperature overnight, concentrated and extracted with dichloromethane (3 x 30 mL). The combined organic phases were dried (Na2 SO4), evaporated to dryness and the residue purified by flash column chromatography with acetone / dichloromethane (3 x 17) to give the title compound. (1H, dt, H-1 *), 7.40 (1H, bs, NH), 7.7-7.35 (10H, m, aromatic H) (1H, d, H-3 *, J 3, p 54Hz), 4.83 (1H, t, GH 3), 4.2 (1H, dt, (2H, m, H-5 ') 2.65-2.1 (2H, m, * H-2'), 1.02ppm (9H, s, tBu). c) 21β, -Pyloxy-5Î ± -fluoro-5-fluoromethyl-5Î ±, -O- (tert-butyldi-phenylsilyl) uridine

A solution of -dideoxy-3-fluoro-5-hydroxymethyl-5,10- (tert-butyldiphenylsilyl) uridine (0.8 g, 1.6 mmol) in anhydrous CH 2 Cl 2 (10 mL) ) was added to a stirred suspension of DAST (0.19 mL, 1.6 mmol) in anhydrous CH 2 Cl 2 (5 mL) under a nitrogen atmosphere at -15 ° C. The reaction mixture was stirred at -5 ° C for 30 minutes and at room temperature for 1 hour. The mixture was poured into ice / water (14 ml), the organic phase separated, washed with water (10 ml), dried (Na2 SO4) and evaporated to dryness. The remaining residue was purified by column chromatography eluting with acetone / dichloromethane (3: 17 and 1: 16) to provide the title compound 200MHz RMMâ,ƒ (dEMEMSO) 11.6 (1H, bs, MH), 7.9 (1H, d, H-6 ), 7.7-7.35 (10H, m, aromatic H), 6.15 (1H, dt, H-1 '), 5.35 (1H, dm,

H-3 ', J 3, J = 54Hz), 4.8 (2H, d, CH 3), 4.25 (1H, dt, H-4', 27Hz), 3.88 (2H, m, ), 2.7-2.2 (2H, m, H-2 '), 1.03ppm (9H, 9tBu). d) 2,3-Pideoxy-3β- (fluoromethyl) uridine

A 1M solution of tetrabutylammonium fluoride in THF (1.6 ml) was added dropwise to a stirred solution of 2, 3, -dideoxy-3, fluoro-5-fluoromethyl-5,10- butyl-diphenylsilyl) uridine (0.33 g, 0.66 mmol) in THF (2.5 mL) at 0 ° C and the stirring was continued for 40 minutes at 0 ° C and 10 minutes at room temperature. The reaction mixture was then applied directly to a silica gel column containing dichloromethane and eluted with tetrahydrofuran / dichloromethane (3: 7) to obtain the title compound. (1H, d, H-6), 6.18 (1H, dt, H-1 '), 5.22 (1H, bs, M), 8.15 4.15 (1H, m, H-4 '), 3.61 (2H, m, H-5'), 2.6 - 2.1ppm (2H, m, H-2 *).

FAB Mass Spec: Observed (M + Na) + 285 *

To a stirred solution of 2 ', 3'-dideoxy-3'-fluoro-5-fluoromethyl-5' - (tert-butyldiphenylsilyl) uridine (prepared as described in Example 1 (step c) above) in dry THF (5 mL) at 0 ° C was added a 1M solution of tetrabutylammonium fluoride in THF (2.5 mL). Stirring was continued at 0 ° C for 45 minutes, and the mixture was evaporated to dryness and the residue was purified by column chromatography eluting with methanol / dichloromethane (1:19). The product fractions were concentrated and the solid was recrystallized from methanol to give the title compound. Mp 142-143 ° C. - 32 - *

microanalysis - Calculated 0.48.17; H, 5.52; H, 12.22%

Found:. (1H, bs, M), 7.9 (1H, s, H-6), 6.2 (15, dt, 1H), 5.33 (1H, dm (1H, m, OH-5 '), 4.17 (1H, dt, H-4 *, J 4, > F = 27Hz), 4.03 (2H, s, (2H, m, H-5 '), 3.23 (3H, s, CH 2 OCH 3), 2.6-2.2ppm (2H, m, H-2').

Example 3 a) 5Î ± -O-Î "6,6-1-2β, 3-dideoxy-3Î ± -fluoro-3-methyluridine

Acetic anhydride (6.2 ml) was added dropwise to a stirred solution of 2α, 3β-dideoxy-3, -fluoro-5-methyluridine (11 g, 45 mmol) in dry pyridine (100 ml) at 0 ° C. The mixture was then allowed to warm to room temperature and stirring was continued for 48 hours. The reaction mixture was cooled by dropping an ice / water mixture and extracted with methylene chloride (3x80 mL). The organic phases were combined, dried (Na2 SO4) and evaporated to dryness to give a solid which was recrystallised from ethanol to give the title compound. Melting point 123Â ° C. (1H, dd, H-3 '), 4.3 (1H, bs, H-6), 6.2 (1H, bs, (2H, m, H-5 '), 2.58-2.3 (2H, m, H-2'), 2.05 (3H, s, OAc), 1.75 ppm (3H, s, CH3). b) 5-O-Acetyl-5-bromomethyl-2 ', 3'-deoxy-3'-fluorouridine

A solution of N, N-bromosuccinimide (0.356 g, 2 mmol) and N-bromosuccinimide (0.356 g, 2 mmol) and N-bromosuccinimide (0.005 g) in dry dichloromethane (15 ml) under reflux under nitrogen, the cooled mixture was evaporated to give the crude title compound which was used immediately without further purification. c), 2?, 3? -Dideoxy-5-ethoxymethyl-3? -fluorouridine.

A solution of 5'-O-ethyl-5-bromo-2-β-dideoxy-3'-fluorouridine (0.36 g, 1 mmol) in ethanol (20 ml) was stirred for 3 hours in nitrogen. After being allowed to stand for 7 days, the solvent was evaporated to dryness and the residue was purified by column chromatography eluting with ethyl acetate. The fractions of the product were concentrated to give the title compound. (1H, s, HH), 7.9 (1H, s, H-6), 6.25 (1H, dt, 1H), 5.35 (1H, dd, H- 3 H), 5.15 (1H, m, OH-5 *), 4.19 (1H, m, H-4 '), 4.09 (2H, s, CH 2 CH 3), 3.65 (2H, ), 3.45 (2H, q, J 2, CH 2 OH), 2.6-2.1 (2H, m, H-2 '), 1.15 (3H, t, CH 2 OH).

Mass Spectrum: Observed m / z 288.

Example 4 a) 5-O-Acetyl-2 H -dideoxy-4-fluoro-4-methylthiomethyluridine

A mixture of 5'-O-acetyl-5-bromoinethyl-2 ', 3'-dideoxy-3', fluorouridine (0.36 g, 1 mmol prepared according to Example 3b) and thiomethoxy (84 mg, 1.2 mmol) in dry dioxane (25 ml) under nitrogen at room temperature for half an hour. The reaction mixture was filtered and the filtrate evaporated to dryness. The remaining residue was purified by column chromatography eluting with ethyl acetate to provide the title compound. (1H, s, NH), 7.6 (1H, s, H-6), 6.2 (1H, dt, 1H), 5.35 (1H, (2H, m, H-5 '), 3.3 (2H, m, CH 2 CH 3), 2.6-2.1 (2H, m, H-2'), 2.08 (3H, s, QAc), 2.00ppm (3H, s, CH3).

Mass Spectrum Observed m / z 332 b) 2 ', 3'-Pideoxy-3' 'fluoro-5-methylthiomethyluridine

A solution of sodium methoxide,

(0.1 ml of a 1M solution in methanol) was added dropwise to a stirred solution of 5,0-acetyl-2 ', 4'-dideoxy-4-fluoro-5-methylthiomethyluridine (0.04 g, 12 mmol) in dry methanol (10 mL) under nitrogen at room temperature. After 45 minutes the reaction mixture

L was neutralized with D9WEX 50 (H) resin. The resin was filtered off, washed with methanol and the filtrate evaporated to dryness. The residue was purified by column chromatography eluting with ethyl acetate to give the title compound.

(1H, bs, NH), 7.85 (1H, s, H-6), 6.2 (1H, dd, 1H), 5.3 (1H, (1H, m, H-5 '), 4.2 (1H, m, H-4'), 3.6 (2H, CH 2 OH), 2.6-2.2 (2H, m, H-2 '), 2ppm (3H, s, CH 2 CHGH 5).

Mass Spec. Observed m / z 290.

Pharmaceutical Compositions

In the following Examples of formulations " Active Ingredient " may be any compound of formula (I) or a pharmaceutically acceptable derivative thereof, for example the compounds of Examples 1 to 4.

Example 5 Compositions for Tablets

The following formulations A, B and C were prepared by wet granulation of the ingredients with a solution of povidone followed by addition of magnesium stearate and compression.

Formulation A mg / tablet mg / tablet (a) Active ingredient 250 250 (b) lactose B.P. 210 26 (c) Povidone B.P,

: > (d) Sodium starch glycolate (e) Magnesium stearate 20 5 500 12 3500

Formulation B (a) Active ingredient (b) lactose (c) Avicel PH 101 (d) Povidone BP (e) Sodium starch glycolate (f) Magnesium stearate mg / tablet 250 150 60 15 20-55 Âμg / tablet 250 26 9 12 _L_ 300

Etoration G mg / tablet

Active ingredient Lactose AmidoPovidone Magnesium stearate 100 200 50 5 4 359

The following formulations D and E are prepared by direct compression of the blended ingredients.

Formulation D mp / capsule

Active ingredient Pre-latinized starch ΪΠΡ15 250

Formulation E

Active ingredient mg / capsule 250 - 36 - 150 100

Lactose

Avieel 500

Formulation F (Controlled Release formulation) The formulation is prepared by wet granulation of the following ingredients with a solution of potidone followed by the addition of magnesium stearate and compression. mg / tablet (a) Active ingredient 500 (b) Hydroxypropylmethylcellulose 112 (Methocel K4'M Premium) (c) Lactose BP 53 (d) Povidone BPO, 28 (e) Magnesium stearate 7 700 The release of the medicament takes place during one period of about 6 to 8 hours and is full after 12 hours.

Example 6 Formulations for Capsules Formulation A A capsule formulation is prepared by adding the ingredients of Formulation B in Example 3 above and introducing into a two part hard gelatin capsule.

Formulation B mg / capsule (a) Active ingredient 250 (b) Lactose B.P. 143 (c) Sodium starch glycolate 25-37 -

(d) Magnesium stearate 2 420

The capsules are prepared by mixing the above ingredients and introducing into a two part hard gelatin capsule.

Formulation 0 (a) Active ingredient (b) Macro gol 4000 BP mg / capsule 250 550 600

Capsules are prepared by melting Macrogol 4000 BP, dispersing the active ingredient in the melt and introducing the melt into a two part hard gelatin capsule.

Formulation D mg / capsule

Active ingredient Lecithin Peanut oil 250 100 100 450

Capsules are prepared by dispersing the active ingredient in lecithin and peanut oil and introducing the dispersion into soft and elastic gelatin capsules. Formulation E (Controlled Release Capsule) The following formulation is prepared for the extrusion controlled release capsules of ingredients (a), (b) and (c) using an extruder, followed by spheronization of the extrudate and drying. The dry aggregates are then re- dressed with a release control membrane (d) and in-

in a two-piece hard gelatin capsule. (a) Active ingredient 250 (b) Microcrystalline cellulose 125 (c) Lactose BP 125 (d) Ethyl cellulose 13 513

Example 7 Injection Formulation Formulation A

Active ingredient 0.200 g

Hydrochloric acid solution, M.I., q.s. for pH 4.0 to 7.0

Sodium hydroxide solution, 0.1M q.s. to pH 4.0 to 7.0 Sterilized water q.s. to 10 ml the active ingredient is dissolved in a large amount of water (35-40 ° C) and the pH is adjusted to between 4.0 and 7.0 with hydrochloric acid or sodium hydroxide as appropriate. The batch is then filled with water and filtered through a sterile micropore filter into a sterile 10 ml (type 1) amber glass vial and sealed with sterilized lids and seals.

Formulation B

Active ingredient 0.125 g

Phosphate buffer, pH 7, sterilized and pyrogen-free, p.b. to 25 ml

Example 8 Intramuscular Injection

Active ingredient 0.20 g Benzyl alcohol 0.10 g -

G-licofurol 75 1.45 g water for injection p.b. to 3,000 ml. The active ingredient is dissolved in glycofurol. The benzyl alcohol is then added and dissolved in the product, and water is added to 3 ml. The mixture is then filtered through a sterile micropore filter and inserted with sealing into sterile 3 ml amber glass vials (type 1).

Example 9 Syrup

Active ingredient 0.25 g

Sorbitol solution 1.50 g G-licerol 2.00 g

Sodium benzoate 0.005 g

Aroma, peach 17.42.3169 0.0125 ml pure water p.b. to 5.00 ml The active ingredient is dissolved in a mixture of glycerol and a lot of purified water. An aqueous solution of sodium benzoate is then added to the solution, followed by addition of the sorbitol solution and finally of the flavor. The volume is perfect with purified water and the mixture is well mixed.

Example 10 Suppository mg / suppository 250 1770 2020

Active ingredient Pure fat, BP (Witepsol H15 · Dynamit Nobel) It is melted 1/5 of Witepsol H15 in a steam jacketed vessel at a maximum temperature of 45 ° C. The active ingredient is aspirated through a 200 μl tube and added to the molten pool using a silver-

are " equipped with a cutting head, until a soft break is obtained. Holding the mixture at 45 ° C, the remaining part of Witepsol H15 is added to the suspension and stirring is continued to give a homogeneous " mixture. The entire suspension is passed through a 250 mesh stainless steel screen and, while stirring, is allowed to cool to 40Â ° C. When it reaches a temperature of 38-40Â ° C, 2.02 g of mix in suitable 2 ml plastic molds. The suppositories are allowed to cool to room temperature.

Example 11 Pessaries mg / pessary 250 380 363 _L. 1000

Active Ingredient Dextrose Anhydrate Potato Starch Magnesium Stearate

The above ingredients are mixed directly and are prepared pessaries by direct compression of the resulting mixture.

Example 12 Antiviral Assay and toxicity (a) MI4 Antiviral Assay and Toxicity

The antiviral activity against Human Immunodeficiency Virus (HIY) was determined according to the method of Pauwels et al., J. Med. Yirol. Methods, 1988 20 309-321 by measuring the ability of the compound to reverse the cytopathic effect of HIY infection. This was determined by a quantitative evaluation of the growth of controlled cells on the fifth day after infection by a tetrazolium (MTT) dye uptake assay. those of subconfluent human lymphocytes I (20-40000 cells /

/ bore) infected with HIY in 96-well microtiter plates were exposed to different dilutions of the drug. After 5 days, a blood absorption assay was performed on the cultures treated with the drug and on cells infected with HIY and MT4 cells infected with an inert. Under the assay conditions, HIY infection caused a very large cytopathic effect and prevented cell growth by more than 80%. The antiviral effect of the drug is reported as the value of 10-50, i.e., as the inhibitory concentration which elutes the protection of 50% of cells from cell death, measured as 50% of the cell growth determined by control of uninfected MI4 cells.

Cell cytotoxicity was evaluated in a cell growth inhibition assay in uninfected MT4 cells or in " true " cells. on a 96-well microtiter plate. An identical number of uninfected cell cells were exposed at different dilutions of drug and the viability of the cells in replication cultures was terminated daily using MTT uptake. The concentration required for a 50% inhibition of cell viability after 5 days is termed CCIB-50. (b) HeLa-GB4 Cell Assay for Evaluation of HI Suspensions to Anti Viral Compounds The susceptibility of HIY to inhibitors was determined by monolayer infection of HT4-6C cells as described by Larder, BA, Chesebro, B. &; Richman, B.B., Antimi crob. Agents Chemother. 1990, 34, 436-441. Briefly, cells were inoculated into 24-well multi-well plates at 5x10 4 cells per well and incubated overnight at 37 ° C in growth medium (DMEM10). The monolayers were infected with 100-200 pfu of cell-free virus in 0.2 ml of BMEM containing 5% fetal bovine serum and antibiotics (BMEM5) and incubated for 1 hour at 37 ° C to allow absorption of virus - 42 -

rus. After this time, 0.8 ml of MM5 (with or without inhibitor) was added to each well and cultures were incubated at 37 ° C for 2-3 days. The monolayers were fixed with a 10% solution of formaldehyde in PBS and developed with 0.25% of violet crystals in order to visualize virus plaques. Individual foci of the multinucleated giant cells (pia cas) were apparent using this development procedure. Values were derived from the plaque reduction percentage curves as a function of the inhibitor concentration.

(c) PBL Assay

HIV assays were performed on human peripheral blood lymphocytes (PBLs) prepared by fractionating fresh human plasma on Bicoll gradients as described by Hartmann et al. Aids Research and Human Retroviruses, 1988, 4, 457-466. Isolated PBLs were stimulated with IL2 and PHA growth factors for 3 days prior to infection with HI. Boi virus-controlled growth after 4 days of incubation at 37 ° C by quantitative ELISA assays of the capsid antisense, P24, Boi incorporated into the medium a range of known molar compound concentrations. The yields of P24 for each concentration are expressed as the percent control and a dose response curve is plotted. From this curve the value of 508 of the inhibitory concentration (IC, q) is estimated.

- 43 -

as a function of HIV-1 (ÂμM) .TOX (ÂμM) Compound 3P MT-4 PB1, HELA-CD4 2β-Dideoxy-31-fluoro-5-methoxymethyluridine 8.4.6.4. 1.89 11.9 500 2 ', 3'-dideoxy-3'-fluoro-5-methylthiomethyluridine 6.4.0.25.1.3 0.16.0.94 4.2 200 2 *, 3'-dideoxy-3'-fluo 0.6.4.2 1.52, 1.63 6.3 200 ro-5-e-toxymethyluridine

- 44 -

Claims (1)

A process for the preparation of a compound of formula (IB) 0 (IB) in which R4 represents a (1-4C) alkylthiomethyl, (1-4C) alkoxy, cyanomethyl, mono-, di- or trihalomethyl group (other than bromomethyl), nitro, 2-haloalkynyl (1-4C) alkoxy or (1-4C) alkylthio; or a pharmaceutically acceptable derivative thereof characterized in that: (A) For the preparation of compounds of formula (IB) in which R 1 represents a (1-4C) alkylthiomethyl, (1-4C) alkoxy, cyanomethyl, mono-, di- or tri-halomethyl (other than bromoethyl), nitro, 2-haloalkynyl, a protecting group of a compound of formula (II) 1} zr · 1 (II) wherein R 1 is a protected hydroxy group and R 2 is equal to R in the resulting compounds of formula (I); (B) For the preparation of compounds of formula (IB) in which R1 is an alkoxy group (I-40), a compound of formula (I ') - 46 - in which Y is a hydroxy group, with an agent (s) and / or under conditions which serve to alkylate the 5-hydroxy group on the uracil base. (C) For the preparation of compounds of formula (IB) in which R1 represents a (1-4C) alkylthio group, reacting a compound of formula (IV) wherein Y represents a group replaceable with an agent (s) and / or under conditions which serve to introduce a (1-4C) alkylthio group at the 5-position. (D) reacting a compound of formula (V): in which is as defined above and Z represents a precursor group for the fluorine group, with an agent (s) and / or under conditions which serve to convert the desired precursor group to a fluorine group; or (E) reacting a pyrimidine base of formula (VI): in which R1 is as defined above, or a functional equivalent thereof, with a compound which serves to introduce the desired ribofuranosyl α-nel at the 1-position of the pyrimidine base of formula (VI); and then either simultaneously carrying out one or more of the following optional conversions: (i) removing any remaining protecting groups; (ii) when forming a compound of formula (IB), converting said compound into a pharmaceutically acceptable derivative thereof; (iii) when forming a pharmaceutically acceptable derivative of a compound of formula (IB), converting said derivative into a compound of formula (IB), or a different derivative thereof. 2. A process as claimed in claim 1 which is characterized in that a compound of formula (IB) wherein R 1 'is alkyl (1-40) thiomethyl or (1-40) alkoxy methyl; or a pharmaceutically acceptable derivative thereof. 3. A process according to claim 1, characterized in that, in particular, the compound 2, 3'-dideoxy-3'-fluoro-5-methoxymethyluridine or a pharmaceutically- % V *. 4. A process according to claim 1, characterized in that, in particular, the compound is 4-dideoxy-3'-fluoro-5-ethoxymethyluridine or a pharmaceutically acceptable derivative thereof acceptable. 5. A process as claimed in claim 1, wherein the compound 2 ', 3'-dideoxy-3'-fluoro-5-methylthiomethyluridine or an ethytically acceptable organic derivative thereof is obtained. 6. A process for the preparation of a pharmaceutical composition which is characterized by incorporating a compound of formula (IA) 1 in which R 1 represents a (1-4C) alkylthiomethyl, (1-4C) alkoxy, o-methylomethyl, mono-, di- or trihalomethyl, nitro, 2-haloalkynyl, (1-4C) alkoxy or 1-40) thio; or a pharmaceutically acceptable derivative thereof when prepared by a process which comprises (A) For the preparation of compounds of formula (IA) wherein R 1 * represents a (1-4C) alkylthiomethyl, alkoxy (1-4C) , mono-, di- or trihalomethyl, nitro, 2-haloalkynyl, a protecting group of a compound of formula (II) in which OR 1 is a protected hydroxy group and X is equal to R 1 in the resulting compounds of formula (I); (B) For the preparation of compounds of formula (IA) in which R 1 represents an alkoxy group (1-4C), reacting a compound of formula (IV) in which Y is a hydroxy group with an agent (s) and / or under conditions which serve to alkylate the 5-hydroxy group on the uracil base. (C) In the preparation of compounds of formula (IA) in which R1 is an alkyl (1-40) thio group, a compound of formula (IV) wherein I is a an agent (js) and / or under conditions which serve to introduce an alkyl (1-40) thio at the 5-position. (D) reacting a compound of formula (V): - 51 - J > (7) in which R4 is as defined above and Z represents a precursor group for the fluorine group, with an agent (s) and / or under conditions which serve to convert said precursor group to a fluorine group; or (E) reacting a pyrimidine base of formula (VI): in which is as defined above, or a functional equivalent thereof, with a compound which serves to introduce ribofuranosyl α-nel at the 1-position of the pyrimidine base of formula (VI); and then either simultaneously carrying out one or more of the following optional conversions: (i) removing any remaining protecting groups; (Ii) when forming a compound of formula (IB), converting said compound into a pharmaceutically acceptable derivative thereof; (iii) when forming a pharmaceutically acceptable derivative of a compound of formula (IB), converting said derivative into a compound of formula (IB), or a different derivative thereof, and associating the resulting compound with formula (I) with one or more pharmaceutically acceptable carriers, to obtain said pharmaceutical compositions. The applicant claims the priority of the British application filed on February 16, 1990 under the 9003543.7. Lisbon, February 15, 1991 - 53 -